In a spread spectrum communication system, a communication device on the transmission side (a transmitter) performs primary modulation on transmission data, and further multiplies data obtained by the primary modulation by a spreading code to perform spread spectrum processing. The communication device then converts a signal obtained by performing spread spectrum processing into a signal with a radio-frequency band, and thereafter transmits the signal obtained by the conversion to a counterpart communication device (receiver). Meanwhile, upon reception of the signal from the counterpart communication device, the communication device on the reception side despreads the received signal by multiplying the received signal by a spreading code that is the same as the spreading code having been used for the multiplication of the communication device on the transmission side, in synchronization with a desired timing, integrates energy of the despread signal over a spreading-code period, and further performs bit determination based on an addition result obtained by adding the integration results.
As a conventional technique applicable to the communication device on the reception side in the spread spectrum communication system, there is a data decoding circuit described in Patent Literature 1 listed below, for example. The data decoding circuit described in Patent Literature 1 listed below utilizes a cross-correlation value to determine a spreading-code period, obtains a bit-data correlation value in a period identical to the spreading-code period so as to accurately perform bit determination, and demodulates the received signal.